Reduction of interferences in immunoassays

Abstract

The present invention relates to a method for determining an analyte in a sample, comprising a) contacting said sample with at least a first and a second detector compound; b) determining the amount of complexes comprising at least one detector compound; and, c) determining said analyte in a sample based on the result of step b), wherein said first detector compound comprises a first binding moiety and a first label, and said second detector compound comprises a second binding moiety and a second label, and wherein the first label and the second label are non-identical. The present invention further relates to a kit for detecting an analyte in a sample, comprising at least a first and a second detector compound for said analyte, wherein said first detector compound comprises a first binding moiety and a first label, and said second detector compound comprises a second binding moiety and a second label, and wherein the first label and the second label are non-identical; and to a device for determining an analyte in a sample, comprising at least a first and a second detector compound for said analyte, wherein said first detector compound comprises a first binding moiety and a first label, and said second detector compound comprises a second binding moiety and a second label, and wherein the first label and the second label are non-identical; and means for determining at least one signal obtained from said first label and said second label; and to the use of a composition comprising at least a first and a second detector compound for detecting an analyte, wherein said first detector compound comprises a first binding moiety and a first label, and said second detector compound comprises a second binding moiety and a second label, and wherein the first label and the second label are non-identical.

Description

[0001]The present invention relates to a method for determining an analyte in a sample, comprising a) contacting said sample with at least a first and a second detector compound; b) determining the amount of complexes comprising at least one detector compound; and, c) determining said analyte in a sample based on the result of step b), wherein said first detector compound comprises a first binding moiety and a first label, and said second detector compound comprises a second binding moiety and a second label, and wherein the first label and the second label are non-identical. The present invention further relates to a kit for detecting an analyte in a sample, comprising at least a first and a second detector compound for said analyte, wherein said first detector compound comprises a first binding moiety and a first label, and said second detector compound comprises a second binding moiety and a second label, and wherein the first label and the second label are non-identical; and to ...

AI Technical Summary

Benefits of technology

[0017]The method of the present invention, in an embodiment, is an in vitro method. Moreover, it may comprise steps in addition to the ones specifically mentioned. In particular, step a) may be preceded by a step of providing a sample, or steps a) and/or b) may comprise addition of further compounds in order to facilitate binding and detection. Furthermore, some or all steps may be assisted by automated equipment. In an embodiment, the method is an immunological method, i.e., in an embodiment at least one of the analyte and the detector compounds are or comprise an antibody.

[0018]The term “biological molecule” is known to the skilled person and, typically, relates to a molecule produced by the metabolism of at least one organism. Accordingly, the term “biological macromolecule” relates to a polymer produced by an organism, in an embodiment, from monomeric precursors. A typical biological macromolecule is a polypeptide, DNA, RNA, or a polysaccharide.

[0019]The term “polypeptide”, as used herein, in an embodiment, includes variants and fragments of the specifically indicated polypeptides. Variants include polypeptides comprising amino acid sequences which are at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the amino acid sequences specifically indicated. The percent identity values are, preferably, calculated over the entire amino acid sequence region. A series of programs based on a variety of algorithms is available to the skilled worker for comparing different sequences. In this context, the algorithms of Needleman and Wunsch or Smith and Waterman give particularly reliable results. To carry out the sequence alignments, the program PileUp (J. Mol. Evolution., 25, 351-360, 1987, Higgins et al., CABIOS, 5 1989: 151-153) or the programs Gap and BestFit [Needleman and Wunsch (J. Mol. Biol. 48; 443-453 (1970)) and Smith and Waterman (Adv. Appl. Math. 2; 482-489 (1981))], which are part of the GCG software packet [Genetics Computer Group, 575 Science Drive, Madison, Wis., USA 53711 (1991)], are to be used. The sequence identity values recited above in percent (%) are to be determined, preferably, using the program GAP over the entire sequence region with the following settings: Gap Weight: 50, Length Weight: 3, Average Match: 10.000 and Average Mismatch: 0.000, which, unless otherwise specified, shall always be used as standard settings for sequence alignments. A polypeptide comprising a fragment of any of the aforementioned polypeptide sequences, in an embodiment, is also encompassed as a polypeptide of the present invention. The fragment is a polypeptide which still is suitable as an analyte or for use in a detector compound as specified elsewhere herein, e.g. has the activity of being a binding moiety as specified elsewhere herein. Accordingly, the polypeptide may comprise or consist of the domains of the polypeptide of the present invention conferring said biological activity. A fragment as meant herein, preferably, comprises at least 50, at least 100, at least 250, or at least 500 consecutive amino acid residues of any one of the aforementioned amino acid sequences comprising at least 20, at least 30, at least 50, at least 80, at least 100 or at least 150 consecutive amino acids of any one of the aforementioned amino acid sequences. The polypeptides of the present invention may contain further polypeptide sequences as well. Specifically, the polypeptides of the present invention may be fusion proteins wherein one partner of the fusion protein is a polypeptide as specified herein. Such fusion proteins may comprise as additional part polypeptides for monitoring expression (e.g., green, yellow, blue or red fluorescent proteins, alkaline phosphatase and the like) or so called “tags” which may serve as a detectable marker or as an auxiliary measure for

Problems solved by technology

In case the concentration of analyte in the sample is high, there is a strong competition, leading to a decreased binding of the specifier to the capture compound, causing signal reduction, which, depending on the test format, leads to a quantitative or qualitative test result.

If there is a signal reduction caused by anti-label interferences, this may cause false-positive results.

Anti-label interferences tend to reduce the signal by binding to the label, causing a reduction in signal yield and, thereby, false-negative results.

In some cases anti-label interferences may also incr